Yeah, uh I have some suggestions for you if you want to make your tournies better/larger with a greater turnout.
1. No round robin. Do brackets or don't do it at all. Make your own brackets. Don't ask people to bring them. That makes you look unprepared and unprofessional.
2. Start the tournament sooner. If you start the tourney at around 12 noon and you have time for doubles, it looks better. If it starts late and there is only one event the tourney looks bad and it makes it seem like it's not worth peoples time. You can still run your regular business even with the tourney going on. Just dedicate the t.v's to smash.
3. Do Doubles and Singles. See number 2 for the reasons why.
4. Make it a monthly. If you make it a reoccurring event then you will establish a group of dedicated smashers that will always show up to your tournaments. Just make sure it doesn't conflict with TSA's Smashacre or cheezit's biweekly and you are good to go.
5. Hype up your tourney more. If you make these changes then for the next thread you can say some thing like, NEW AND IMPROVED TERRABITE TOURNEY!!! Something that has a hook and will make people say," hmm I should go to this thing.
6. Be more organized. You said it starts at 6 pm. But we didnt get started until 6:30. You need to have your ducks in a row. Know how the brackets will be run. Have enough cubes and copies of Smash, etc.
7. Don't gank the pot. I have no idea how much was taken from the pot. But a general rule of thumb is that taking more then 40% of the pot is usually viewed by the community as greedy. So yeah, don't gank the pot. This isn't an accusation, just something that you should know.
That's basically it. If You guys do all that. I can pretty much garuantee you that the next tourney you guys have will get at least 25 people.